Variable-speed drive



Sept. 4, 1951 w. M. SCHWEICKART 2,566,997

VARIABLE'SPEED DRIVE Filed Aug. 20, 1946 3 Sheets-Sheet 2 amnm p 1951 M. SCHWEICKART VARIABLE-SPEED DRIVE 3 Sheets-Sheet 5 Filed Aug. 20, 1946 ATTO R N EY lllllll i H w Patented Sept. 4, 1951 VARIABLE-SPEED DRIVE William M. Schweickart, Mentor, Ohio, assignor to Speed Selector Inc., Cleveland, Ohio, a corporation of Ohio Application August 20, 1946, Serial No. 691,812

Claims.

This invention relates to variable speed transmissions and more particularly to those of the belt driven variable speed type.

An object of the invention is to provide a variable speed transmission of the belt type which will be adaptable to various drives and dependable in maintaining each predetermined performance under the variable conditions of service.

It is a further object of this invention to provide a belt driven variable speed transmission automatically controlling the speed variation to maintain a set speed irrespective of changes in the load.

It is a further object of this invention to provide a belt. driven variable speed transmission in which the ratio between input and output speeds will not be changed by a variation of the load.

These and other objects and features of this invention will become more apparent upon consideration of the description taken with the following drawings in which:

Fig. 1 is a vertical sectional view of a variable speed drive;

Fig. 2 is a partial end view of the variable speed drive as seen from the right of Fig. 1;

Fig. 3 is a horizontal sectional view taken on line 33 of Fig. 2;

- Fig. 4 is a horizontal sectional view similar to Fig. 3 with the parts in a different position;

Fig. 5 is a partial vertical sectional view taken on line 5--5 of Fig. 1; and

Fig. 6 is a vertical sectional view of a modification of this variable speed drive.

In general, the variable speed transmission of this invention comprises a stationary support carrying two separate rotatable means connected by belts and one of which is driven by outside means and the other drives a power take-01f.

With reference to Fig. 1, a hub I suitably supported has fastened to it a casing 2 and two discs 3, 4 of a V-pulley. The disc 4 is keyed to the disc 3 by pins 6 to permit axial but not angular motion between the discs. The hub I and pulley 3, 4 are formed with an annular passage through the center into which is fitted a hollow shaft I. The shaft 1 is rotatably supported in the hub I and pulley 3, 4 on two bearings 8 and 9. The shaft 1 carries at one end discs II and I2 of a V-pulley and at the opposite end an output pulley ment between the discs. The disc II is connected with the disc 4 to pulley 3, 4 through the bearing I3. The disc II is slidably fitted on a portion of shaft 1 and has a bushing I4 on which the bearing 9 is seated. The disc I2 is fastened on the 'end of shaft 1 and connected to the disc II by pins I6 to permit axial but not angular displace- 9 which seats on bushings I4 and H of discs II and 4 respectively. The bearing 9 holds discs II and 4 as a unit axially but permits angulardisplacement.

On the opposite end of the shaft I a flange I8 is provided and engages a member I9 through steel balls 2| in pockets 22 provided in the flange I8 and the member I9. The pulley I3 is fastened to the member I9 and the bearing 8 seats on a flange 24 of the member I9. The end of the hollow shaft I is supported by the bearing 8 which also seats on flange 26 of the hub I. In the hollow shaft 1 a rotatable quill 21 is mounted on bushings 28 and 29. A drive shaft 3| is wedged in the quill 21 by a collet 30 and secured by a lock nut 32 at the opposite end. The plate 33 is secured to a collar 34 fixed on the quill 21. The plate 33 carries a crank member which is also supported by a plate 31. The plate 31 is rotatably supported by a. bearing 38 on a shoulder 39 of the disc 3. An axle 36 of the crank 40 carries two V-pulleys composed of discs 42, 43 and 44, which are rotatably mounted on the axle 36. The left disc 43 of pulley 42, 43 and the right disc 44 of the pulley 44, 45 are joined on sleeves 41 which slide on bolts 48 to which discs 42 and 45 are fastened. The entire assembly of plate 31 and 33, axle 36 and shaft 3I rotate as a unit supported by bushings 28 and 29 and bearing 38. Pulley 42, 43 is connected to pulley 3, 4 by belt 49 and pulley 44, 45 is connected to pulley II, I2 by belt 50.

To provide adjustment of the tension on the belts 49 and 58 by moving the axle 36 either toward or away from the pulleys 3, 4 and I I, I2, the crank 49 is eccentrically pivoted in the plates 33 and 31 on pins 4| so that when the axle 36 and crank 40 turn on the pins 4| they move radially with relation to the pulleys 3, 4 and II, I2. I A counterweight 68 positioned opposite the axle 36 on an axle 89 is eccentrically pivoted in the plates 33 and 31 of a crank I0 turning on pins 1|. The movement of the crank I0 on the pins 'II provides an adjustment of the counterweight 68 radially with relation to the pulleys 3, 4 and II, I2 which may be indexed to match the adjustment of the axle 36.

The member I9 and the flange I8 are con-,- nected to steel balls 2I in pockets 22 whichhave inclined sides. The flange I8 on the hollow shaft I moves integrally with the disc I2 of the pulley II, I2. Axial movement of the hollow shaft 1 and the flange I8 and the disc I2 increasesand decreases the depth of the .V in the pulley and 3 consequently the elfective diameter of the pulley for the belt 50. An end view is shown in Fig. 2 of part of the flange I8 as seen from the right of Fig. 1. Insets 55 in the flange I8 encircle the flange with steel balls 2| shown in dotted outline, A limit pin 55 on the member I9 protrudes into a slot-'51, in the perimeter of the flange I8 limiting the amount of angular displacement between the output pulley I3 and. the shaft 1. In a horizontal sectional view Fig. 3 shows one of the steel balls 2| in thepockets 22 when the transmission is at rest. In Fig. 4 the pockets 22 of Fig. 3 are shown moved in relation to each other as they would be if a high torque on the hollow shaft I caused an angular displacement between the shaft I and the output pulley I3. The efi'ect of this relative motion between the pockets in the flange I8 and member I9 is to roll the steel ball 2| up the inclined sides and-force the axially movable flange I8 away from the'minber I9 and cons'equently close the V of thediscs II and" I2 thereby increasing the-'efiectiv'e diameter of the pulley II, I2 an'dincreasing its speed-or counterbalancing a decrease in the effective diameter caused by stretching of the "belts 49' and 50. As a result when an overload is placedon the output pulley I3 displacement takes place between the pulley and shaft 8 and thepulley I I, I2 tightens the belt 50in proportion to'the load placed on the transmission. This takes up any slack in the belts 50 and 49 and-maintains the speed of the output p'ulleyI 3 unvaried by the torque-applied.

"Inoperation motion-is applied tothe transmission through thedrive' shaft 3| which turning the 'pla'te'33' revolves the axle around the central pulleys 3, 4 and II, I2: A-V=belt 49 connects pulley 42,43 with stationarypulley 3; 4- causing the pulley 42, 43 to rotate 'on axle 36 and in turn rotate pulley 44,45 which'is-bolted to itpA V-belt 50 over the pulley 44; 45 transmits the motion to pulley II, I2 and turning-hollow shaft I drives the output pulley'I3 through the "steelballs'2l. The gear ratio'and 'sp'e'edreduction obtained on passing motion through this pulley'and belt'arrangement depends upon-the difference in the speeds of the pulleys-which in turn depends on the relative efiective diameters ofthe pulleys. The V-belts 49' and'50- passing over the pulleys exert a constant tension'to' separate the disc's. As thedis'cs 4 and I2; 42"and45, 43 and 44 are fastened to move together axially the tension on the belts acts to counterbalance the separation of the discs. The speedandth'e'direction of the output pulley'I 3 is'deterinined by the relative speeds of the belts over the pulleys depending upon the sizes and angles of the pulleys and the length of the belts.

By the same adjustment the belt in pulley II, I2 is pinched outward by closing the V between discs II and I2 increasing the effective diameter of the pulley and increasing the tension on the belt 50 to draw it into the pulle 44, 45. The concomitant slack of belt 49 and tautness on belt 50 cooperate to move the attached discs 43 and 44 to the right increasing the efiective diameter of 42, 43 and decreasing the diameter of pulley 44, 45. Thus, the ratio between pulleys 3, 4 and 42, 43 is altered in one direction and the ratio between belts II, I2 and 44, 45 is altered in the opposite direction. As pointed out above, depending upon the sizes and angles of the pulleys and the length of the belts, the adjustment obtained by the worm gear 52 may increase or decrease the speed of the output pulley I3 or reverse it.

The casing 2 has a removable cover 62 of thin metal fastened to the plate 63 by thumb screws 64 in flanged connections for easy removal and ready access to the belts and puleys. Ventilating open. ings 65, 66 and 6'! in cover 62 and plate 63 providecooling by currents of air preventing undue temperature rises.

In Fig. 6 the modified structure is shown in which the applied reference numerals are -100 above the comparative figures of the numerals appearing in Figs. 1 to 5. In this Fig. 6 the stationary hub IIII is composed of an extension of a disc I03 to which is clamped a casing I02. A suitable support is provided for the hub IM and casing I02. A disc I04 forming with disc I03 v a pulley I03, I4 is fastened on pins I06 sliding I28 and I29.

' An adjustment of the discs, the position of the belts and the ratios-betwee'nthe pulleys is obtained by regulating a worm gear 52 turning a worm wheel 53 as shown in-Fig. 5. Referring again to Fig. l the worm gear 52 isshownin hub I turning the worm wheel 53 which sliding in helical grooves 54 an 'extension'ofdisc 4 cause the disc 4 to be moved'axially either left or right depending on the motion of the wormge'ar 52.v The axial connection of the discs 4 and II effects adjustment of the disc II and the pulley II, I2 by the worm gear 52 also.. Thus moving the discs '4 and II to the left opens the pulley 3, 4 and decreases the effective diameter lowering the belt into the pulley 3,4 and easing the tension to permit the belt 49 to: move toward pulley 42, 43

thus changing the ratio between these pulleys.

in the disc I03 and permitting axial but not angular movement between the discs-I 03 and I04; The pins I05 are bolted to a ring I05 which is threaded on a screw I35 turned by a handw-heel I52 to move the ring I05, pins I05 and disc I04 axially of the pulley I03, 14- The pulley I03. I04 is provided-with a centraliannular passage which supports a tapering arbor I2 in bearings The arbor I21 has fitted into-its right end a drive shaft I3| tightened by a 'c'ollet I30. A disc III fitted over arbor I-2I.slides axially on the arbor 1-21- and is held by-dise I04 through bearing'II to slide axially with the disc I04, but permitting angular displacement between discs I04 and III. -A "ring II4 with a flanged portion |I5 is fastened to the arbor I21. The ring H4 is provided with a shoulder on which a disc I I2 is slidably supported to form pulley II I, II2 with the disc III The discII2 is held in place by a V-belt I49 and is connected to the flange II5 through balls I2| in pockets I22. Pins H6 in disk: II2 protrude through discs II I and permit disc III to move axiallybut not angularly in relation to the disc II2. 'An. input pulley H3 is mounted on the arbor I21: on two bearings I 08 and I09. A plate I33 is fastened to the pulley H3 and a second plate I3! is car'- ried on the hub I0| by bearing I38. The plates I33 and I3? carry crank I40 on which are rotatably mounted pulleys I42, I43 and I44, I45 on axle 136. These pulleys are connected to pulleys I03, I04 and III, 2 by 1061155149 and I50. A'lug I46 on the casing I02 providesa connection with a torque arm which gives the. casing increased stability. In operation power is. transmitted through this modification by being-applied'to the pulley I'I3 causing the axle I36 to revolve around the central pulleys I03, I04 and III;, II2; The pulley I44, I45 being connected itostationary pulley I03, I04 by belt I50 iscaused :toirotate bythe revolution of the axle I 36. This rotation in turn rotates placement of disc the pulley I42, I43 which turns'th'e' pulley HI, H2 to which it is connected. .{Ihrough the steel balls l2! the pulley I I I, H2 drives the shaft l3l.

Adjustment of the effective diameters of pulleys of this modification is obtained by turning the handwheel I52 and moving the discs 104,; Ill axially. The steel balls I21 in inclined pockets I22 in the disc H2 and flange ll5 provide a torque compensating motion when an overload is placed on the shaft [3| by; utilizing the dis- H a d fla ge H5 igcl s the V of pulley ll l, ll 2 andcompensatefon-a changein-th el I49. andg fvfl-c In installations where a supply of power and machine to be driveniare' closetogether it is advantageous to apply and take off the powerfrom the same side of the transmission as shown'in the described embodiments of this invention. It is also advantageous for the transmission to be compact, taking up a minimum amount of space and simple in mechanical principle to reduce required attention and repair. These advantages are found in applicants invention as disclosed herein.

By means of the torque compensating device disclosed the application of high torque loads on the output means at very low speeds is made possible without variation in the output speed. Ordinarily where the load turned by the transmission is varied at low speeds the speed of the output rotation is correspondingly changed. The variation in speed is caused by a change in position of the V-belts in the pulleys when a greater torque is applied to the pulley as when the load on the output pulley is increased. To avoid this variation and provide a constant output uninfluenced by changes in the output force to be exerted a compensating means has been devised, an embodiment of which has been disclosed.

By the nature of the construction as the load placed on the output pulley is increased the balls 2| roll up the angular sides of the pockets 22, thus forcing the output shaft to close the V of the driven pulley. This increases the ratio between that pulley and the mating pulley on the revolving axle and also at the same time tightens the belt on those pulleys. Furthermore, if that belt is automatically tightened it also tightens the second belt connecting the other set of pulleys. The effect of this is that the belts can be run loosely under light or normal loads but as an overload is placed on the unit the belts are automatically tightened in proportion to the load placed upon the unit. Thus, it is possible to maintain a constant speed regardless of the load without the use of springs. The action of the compensating means causes the belt to ride at a higher pitch diameter in the driven pulley which has the effect of increasing the output speed. By the proper shape of the pockets the output speed remains constant for varying torque loads.

Another feature of the torque compensating means is the correcting effect compensating for the creeping of the belts on the pulleys. At low output speeds the ratio between the pulleys is only slightly greater than 1:1. Because of the normal creep in the belts the slight difference in the ratios become closer to 1:1 causing a noticeable reduction in output from no load to full load. The torque compensator automatically maintains throughout varying loads the set ratio thus maintaining substantially constant speeds under the conditions of load variation.

As above described the torque load on both sheave faces is applied to displace the compene sator balls 2 l, the pins maintaining a fixed angu-' lar displacement of both sheave faces with. rela-.; tion to the mating compensator pockets 22. The sheaves of the pulley on which the torque, is compensated may be angularly' independent of each other so that the torque on only one sheave is utilized for angular displacement with relation to the compensator pockets and actuating the compensation.

It will alsobe understood that the mechanism may be altered or revised without departing from the principles of the invention as disclosed herein. It is, therefore, intended that the invention not be limited other than by the scope of the appended claims.

I claim:

l. Ina variable speed belt drive the combination with a stationary casing,of arotary sheave frame in said casing and having outer rotary sheaves spaced from the axis of said rotary frame, drive means for said frame at one side of said casing, a stationary sheave in said casing, a rotary driven sheave in said casing having relatively shiftable halves Varying the pitch diameter of said sheave, a driven shaft connected to said driven sheave and coaxial with said drive means, belt connections between said stationary sheave and said outer rotary sheaves, belt connections between said outer rotary sheaves and said rotary driven sheave, said coaxial drive means and driven shaft being sleeved one within the other to extend from the same side of said variable speed drive, and means responding to variations in torque applied by said drive comprising an axially fixed disk and an axially movable disk which is connected to one half of said driven sheave and rotary means v between said disks varying the axial spacing thereof and of said halves of said driven sheave to control the relative speed between the input and output.

2. In a variable speed belt drive the combination with a stationary casing of a rotary sheave frame in said casing having outer rotary sheaves spaced from the axis of said frame, a drive shaft for said frame supported in said casing and coaxial with said frame, a stationary sheave, a rotary driven sheave in said casing and coaxial with said drive, a driven disk adjacent said driven sheave and connected to an output shaft, belt connections between said stationary sheave and said outer rotary sheaves, belt connections between said outer rotary sheaves and said rotary driven sheave, matching cup-shaped recesses in opposing faces of the driven sheave and disk curving to increasing inclination at each side of the bottom of the cup and balls in said recesses actuated by variations in torque applied by said drive to ride upward along said curved surfaces and wedge said driven sheave and disk apart, shifting one of said belt connections radially in the axis of rotation of said rotary sheaves to control the relative speed between the input and output.

3. A variable speed drive comprising co-axial rotary driving and driven members one surrounding the other, a sleeve mounting forming a bearing between them at one side of said drive, a rotary supporting means co-axial with said members and on one side of said mounting and rigidly connected to said driving member, a non-rotatable support carrying a non-rotatable inner pulley co-axial with said members, a rotary inner pulley co-axial with said non-rotatable pulley and connected to said driven member, a pair of outer 'iiulleys carried by said rotary supportin means, all of said pulleys being Y -pulleys having relatively adjustable disks, belt means betw en the outer and inner pulleys, and means for simultaneously adjusting the pitch diameters of the inner pulleys during rotation of said .su-pnortin means to vary the relative rates of rotation of said driving and driven members.

4. A variable speed drive as set forth in cla m 3 in which the rotary driven member is sleeved within the rotary driving member.

5. A variable speed drive as set ferth in claim 3 in which the rotary driving member sleeved within the rotary driven member.

WILLIAM SQHWEIGKART.

REFERENCES CITED The following references are of record in the file of this patent:

8 UNITED STATES PATENTS Number Number 

